I took my Jeep for its first long ride today.
I watch my gauges closely!
I am always at 14V on the factory gauge in the dash.
Well....driving along it dropped all the way down to 9, and the "check gauges" light came on.
I shut everything off, and drove it home.
I used my good ole radio shack voltmeter.
I am showing 13.3 at idle, and 13.6 volts under throttle??
I turned the jeepster off, and turned it back on, and it went back to 14 on the dash gauge, and the light went out? Like it threw a fit or something.
Are my readings okay? Is 13.6 under throttle sound right? I hope my alternator is not on its way out.
I know my other car, I ran out and checked, goes to 15V under throttle.

 

A little low...
Check grounds and alternator cables.

 

I thought that seemed low. I am gonna grab dinner. And head up to the garage. I will clean all the cables, and see what happens.
The battery looks new, and the cables on the battery are really clean. Doesn't look easy to get to the alternator, to service it.

 

Easy test to see if your alt is operating is take a long extension or wrench and hold it close to the back of the alt. if the alt is charging correctly it will have a magnetic charge and pull the wrench or what ever into it. If it doesnt have that pull then the alt is dead. if it does and your still dropping off then your have a loose connection.

 

Just don't let the wrench hit the plug on back of alt. and contact metal. You could short it out or worse.

 

Or swing by a parts store and have them load test it. safer.

 

Mine read 14.48 at the battery idling.

 

I am heading up now, and checking the connections. And see if one is loose. It was fine, and all of a sudden, it got nutty. I am broke now. I hope it does not need one. They seem pricey.
Defiance....I thought it should be higher. Yours is almost 15.0. Thats what I thought!

 

Neat magnet trick, but the volt meter will tell all you need, 13.8 is a good #. Guess you know, use to be common to repair or rebuild them. You might just need brushes.

 

14-15 is the norm but 13.6 volts is fine to charge a battery. As mentioned clean and tighten all the connections and see what happens.

 

Buy a $10 digital multi-meter at the local hardware store.

Switch it to 20-volts and check the voltage of the battery with the engine off. A good battery will usually read around 13.5 volts just sitting.

Next, start the engine and check the voltage from the alternator. It should be putting out 14 or a little more volts.

If somethings not right head to the autoparts store. The load testers they have will be able to tell you if the battery or alternator is bad.

I just had to replace the battery in my wife's car. The thing would not start. I replaced the starter, relays and even the crank sensor. I finally gave up and called a wrecker to have it towed to the dealer. We discovered the battery had an internal fault. The volt meeter showed it was holding 13.6 volts but as soon as a load was put on it it would die. Thankfully replacing the battery was a lot cheaper than all the other problems I was imagining.

 

Not sure about that. I work in a truck parts store and sell batteries daily and we always check them all before we let someone take them and they normally test in the mid 12 volt range.

 

12.7, about 2.2 V/ cell @ room temp.

 

x2

 

Programbo: Your right, I made a typo. It should be 12.5. Sorry for any confusion.